The present invention relates to a compound useful as an ingredient of a resist composition used for preparation of semiconductor elements and the like, which can reduce substrate dependence of the resist composition, and to a resist composition in which the compound is incorporated.
In compliance with the requirement for ultra-fine processing according to high integration of semiconductor devices, the light source of exposure used in lithography processes has recently been changed from i-line (365 nm) to one having shorter wavelength such as KrF excimer laser (248 nm), ArF excimer laser (193 nm) or electron beam. In accordance with the change from high-pressure mercury lump to excimer laser as the exposure source, the resist composition to be used is required to be high sensitive and thus so-far used dissolution-inhibiting resist has been replaced by a chemically-amplified resist composition. In chemically-amplified resist compositions, an action of an acid generated by actinic radiation takes an important role, and therefore influence by the kind of the substrate is often observed, which has not been come into matter in dissolution-inhibiting resist compositions. Namely, in a case of a special substrate such as SiN, TiN, SiON, BPSG and a strong basic organic anti-reflective film, a basic substance and water generated from those substrate inactivate the generated acid on their surface, and consequently no good pattern can be obtained. For this reason, this substrate dependence has been a serious problem in production of semiconductor, devices. In order to dissolve this problem in chemically-amplified resist compositions, there have been proposed use of an organic carboxylic acid such as salicylic acid (e.g. Japanese Patent Publication-Kokai-No. 262721/1996, No. 160247/1997), use of an organic carboxylic acid such as diphenolic acid (e.g. Japanese Patent Publication-Kokia-No. 207066/1998, No. 20504/1998) or an imide compounds such as succinimide (e.g. Japanese Patent Publication-Kokai-No. 44950/1999) and the like. However, addition of salicylic acid, etc. causes a problem concerning stability of a resist solution, and addition of diphenolic acid causes such a problem that almost no reduction of substrate dependence is attained. Further, addition of succinimide, etc. can attain reduction of substrate dependence on some kind of substrates but the reduction is still not enough. Such being the circumstances, it has strongly been desired to develop such chemically-amplified resist composition as capable of forming a rectangular pattern even on a specific substrate just like on an ordinary substrate including an oxide film substrate and organic anti-reflective film (namely no substrate dependence is observed) and being excellent in dimension adjustability and solution stability.
Under the situation, the problem to be solved by the present invention is to provide a resist composition which can form a rectangular pattern even on a special substrate such as SiN, TiN, SiON, BPSG and a strong basic organic anti-reflective film and is excellent in dimension adjustability and solution stability.
For the purpose of attaining the object mentioned above, the present invention comprises the following embodiments.
(1) An agent for reducing substrate dependence of a resist composition, which comprises a compound shown by the following general formula [1]: 
xe2x80x83wherein R41 is a hydrogen atom or a methyl group, R42 is a hydrogen atom, a methyl group, an ethyl group or a phenyl group, R43 is a straight chained, branched or cyclic alkyl group having 1 to 6 carbon atoms, and n is 0 or 1.
(2) A method for reducing substrate dependence of a resist composition, which comprises incorporating as an agent for reducing substrate dependence a compound shown by the following general formula [1]: 
xe2x80x83wherein R41, R42, R43 and n have the same meaning as above.
(3) A resist composition, which comprises a) a compound shown by the following general formula [1]: 
xe2x80x83wherein R41, R42, R43 and n have the same meaning as above, b) a polymer which becomes soluble in an aqueous alkaline developing solution by a chemical change by an action of an acid, and c) an acid generator (hereinafter abbreviated as the resist composition-1 of the present invention).
(4) A resist composition, which comprises a) a compound shown by the following general formula [1]: 
xe2x80x83wherein R41, R42, R43 and n have the same meaning as above, b) a polymer soluble in an aqueous alkaline developing solution, c) an acid generator, and d) a compound which becomes soluble in an aqueous alkaline developing solution by a chemical change by an action of an acid (hereinafter abbreviated as the resist composition-2 of the present invention).
(5) A resist composition, which comprises a) a compound shown by the following general formula [1]: 
xe2x80x83wherein R41, R42, R43 and n have the same meaning as above, b) a polymer soluble in an aqueous alkaline developing solution, c) an acid generator, and d) a cross-linking compound which can make a polymer hardly soluble in an aqueous alkaline developing solution by a chemical change by an action of an acid (hereinafter abbreviated the resist composition-3 of the present invention).